Basic implementation of road based transfers.

This adds the models and UIs for creating ground unit transfer orders.
Most of the feature is still missing:

* The AI doesn't do them.
* Transfers can move across the whole map in one turn.
* Transfers between disconnected bases are allowed.
* Transfers are not modeled in the simulation, so they can't be
  interdicted.

https://github.com/Khopa/dcs_liberation/issues/824

qt_ui/windows/basemenu/QBaseMenu2.py

@@ -19,6 +19,7 @@ from qt_ui.uiconstants import EVENT_ICONS
 from qt_ui.windows.GameUpdateSignal import GameUpdateSignal
 from qt_ui.windows.basemenu.QBaseMenuTabs import QBaseMenuTabs
 from qt_ui.windows.basemenu.QRecruitBehaviour import QRecruitBehaviour
+from qt_ui.windows.basemenu.NewUnitTransferDialog import NewUnitTransferDialog
 
 
 class QBaseMenu2(QDialog):
@@ -88,6 +89,11 @@ class QBaseMenu2(QDialog):
             runway_attack_button.setProperty("style", "btn-danger")
             runway_attack_button.clicked.connect(self.new_package)
 
+        if self.cp.captured and not self.cp.is_global:
+            transfer_button = QPushButton("Transfer Units")
+            bottom_row.addWidget(transfer_button)
+            transfer_button.clicked.connect(self.open_transfer_dialog)
+
         self.budget_display = QLabel(
             QRecruitBehaviour.BUDGET_FORMAT.format(self.game_model.game.budget)
         )
@@ -180,5 +186,8 @@ class QBaseMenu2(QDialog):
     def new_package(self) -> None:
         Dialog.open_new_package_dialog(self.cp, parent=self.window())
 
+    def open_transfer_dialog(self) -> None:
+        NewUnitTransferDialog(self.game_model, self.cp, parent=self.window()).show()
+
     def update_budget(self, game: Game) -> None:
         self.budget_display.setText(QRecruitBehaviour.BUDGET_FORMAT.format(game.budget))